It is known to drive boats with an electric motor. It is also known to control the drive level of the electric motor by means of a device for specifying the drive level wherein the specification of the drive level is implemented, for example, by means of the specification of the power and/or the torque and/or the rotary speed of the electric motor. In order to specify the drive level by means of the operator, in principle, two different possibilities are known:
With a boat drive constructed as an outboard motor with an electric motor, it is known to specify the drive level of the electric motor by means of a twist grip which is provided on the end of a tiller mounted directly on the outboard motor. The operator of the outboard motor can then specify in a per se known manner with the tiller, both the direction and the drive level of the motor.
It is also known to provide a remote throttle device in which a drive lever is provided spaced from the boat drive to be controlled and with which the drive level of the electric motor can be specified. Typically, the remote throttle lever is arranged on a control stand of the boat so that it can be easily operated by a driver whilst the driver also operates the steering wheel. A remote throttle device is used, in particular, when the motor is inaccessibly installed in the boat—for example, as a built-in motor with a shaft drive, as a built-in motor with a Z-drive, as a built-in motor with a sail drive or as a pod drive arranged substantially outside the boat. A remote throttle device can however also be used for controlling an outboard motor. The drive level of the controlled electric drive is herein typically steplessly settable according to the setting of the drive lever.
For controlling a boat drive, a plurality of remote throttle devices can also be provided, arranged at different positions on the boat—for example, at two different control stands or on the tiller and on a control stand.
Typically, such devices have a base element rigidly connected to the boat and a drive lever operable by hand, which is pivotably articulated on the base element. During the pivot movement about the pivot axis, the drive lever acts upon a drive transducer—for example, in the form of a sensor—by means of which the power electronics of the electric motor can be controlled. Through the positioning of the drive lever, the drive level at which the electric drive is to be operated can accordingly be set by the operator. In a zero setting of the drive lever, the electric drive stands still. Through an actuation of the drive lever by hand from the zero setting, the electric drive is operated at a drive level according to the position of the drive lever.
The drive lever can be moved and positioned in a range that is delimited by the zero setting and a maximum setting in which the electric drive is operated at its maximum drive level. With a correctly configured system and, in particular, a correctly matched propeller, the maximum drive level also accords with the nominal power of the electric drive. The nominal power of the electric drive, also called the continuous nominal power is herein the maximum power that can be output on proper operation without any temporal restriction without impairing the operating life and safety of the electric drive, the power electronics and the battery bank. The aforementioned range between the zero setting and the maximum setting is typically provided for driving the electric drive in forward operation.
In addition, such devices typically have a reverse setting of the drive lever to specify a reverse running of the electric drive. The reverse setting is settable with a movement of the drive lever from the zero setting in the opposite direction from the aforementioned forward operation range. The drive unit, typically a propeller, of the electric drive generates a force according to the setting of the drive lever which acts in the opposite direction from the force generated during forward drive.
It is also known that electric drives can be temporarily operated above their nominal power rating without any damage occurring, which can be caused, for example, by overheating of the electric drive or a battery bank of the electric drive. Through the limitation of the power control of the electric drive of the boat to its nominal power, the maximum acceleration values thereby providable or the maximum thrust thereby providable in the short term are thus limited to the values usable at nominal power, so that the power capacity of the electric drive of the boat cannot be optimally exploited for all situations.